Manufacturers process and test semiconductor or integrated circuit (“IC”) devices using various types of automated machinery. Before IC devices are shipped to wholesalers or consumers, they are usually tested for performance and inspected for physical defects. One physical defect that is important to identify is the presence of bent leads on leaded devices such as quad flat packages (“QFP”), thin small-outline packages (“TSOP”) and other types of IC packages.
Generally, mechanical systems or basic camera systems are employed to identify bent leads. However, current mechanical and camera systems are limited in their ability to detect bent leads accurately. In one conventional mechanical system, 3D lead inspection is performed by placing the IC device on a pedestal in front of a camera to ensure a lighting angle pattern. However, placing the IC device on the pedestal makes the inspection slower. In a second type of conventional mechanical system, an interferometer is used to create interference patterns on the IC device leads. To obtain the required resolution, the camera must take multiple images or use different angles of lights to get the 3D lead information of the IC device. This also slows down the inspection process. In a third type of conventional mechanical system, a laser generates an angular projected pattern on the IC device leads. Use of the laser to generate a 3D profile slows down the inspection process and increases the space requirements. In a fourth type of conventional mechanical system, a side view prism views the leads from a side and projects side view images on a front view image. However, the setup is complicated and expensive. In addition, the inspected device must be stopped in front of the camera's field of view. In many cases, the device has to be inserted into a prism fixture to obtain side view images.
Therefore, it would be desirable to provide a reliable, accurate and relatively quicker (i.e., on the fly) 3D lead inspection imaging apparatus capable of accurately detecting bent leads on a leaded device such as a QFP, a TSOP, or any other type of surface mount IC package using a single image to obtain 3D lead information.